Power plant



ou. 9, 1945.- l H H, SPENCER 2,386,638

` POWER PLANT Filed Feb. 9, 1944 5 sheets-sheet 1 Ef ,64 p28 FA T . ATTORNEY Oct. 9, 1945.

H. H. SPENCER POWER PLAN/r Filed Feb. 9, 1944 5 Sheets-Sheet 2 A TTORNE Y Od. 9, ,1945. H H SPENCER 2,386,638

POWER PLANT Filed Feb. 9, 1944 Ssheets-sheet 5 /NVENTOR By H H. 'SPENCER auf@ A TTQRNEY Oct-9,1945. HfH. SPENCER- 2,386,638

POWER PLANT Filed Feb. 9, 1944 5 Sheets-Sheet 4 /NL/ENTOR By H H SPENCER Oct. 9, 1945.

H. H. SPENCER POWER PLANT 5 Sheets-Sheet 5 Filed Feb. 9, 1944 /Nl/EN TOR HH SPE NCE Patented Oct. 9, 1945 POWER PLANT Harry H. Spencer, Springfield, N. J., assignor to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Application February 9, 1944, Serial No. 521,649

(creen-3o) 9 Claims.

This invention relates to electric power genererating plants and particularly to automatically controlled power plants of the type employed in telephone communication systems.

Long distance telephone communication systems, such as transcontinental carrier telephone systems, require repeater stations at more or less regular intervals throughout their length to provide the necessary amplication of the signal carrying currents. Some of these repeater stations may be located, necessarily, in remote sparsely settled parts of the country where there is no commercial source of power available. The chief source of power for the current consuming apparatus, such as amplifiers, fans, heaters, etc., commonly used at such stations, are electric storage batteries which are maintained continuously charged, or are charged at regular intervals, as the charge is depleated by the load, by some auxiliary local source of direct current. In general, the remotely located repeater stations are unattended so that the facilities for charging the storage batteries must necessarily be controlled automatically in a manner such that an uninterrupted supply of power is insured, and should function continuously and effectively with a mim'- mum of maintenance.

It is the object of this invention to provide an improved electric power generating plant which functions automatically to maintain an uninterrupted power supply at a station at which commercial power service and continuous maintenance are not available.

In the power supply system of this invention, the main power source comprises an electrical storage battery which supplies the various instrumentalities located at a repeater station with current, and a pair of internal combustion engine-driven generators are relied upon to maintain the battery voltage within predetermined levels as required by the load supplied thereby.

In accordance with a particular feature of the invention, suitable controls are provided which function automatically to render the two internal combustion engine-driven generators available, alternately, to charge the battery. More particularly, a pair of interacting relays are provided which function to preclude the possibility of one of the engine-driven generators being employed for successive charging operations and to thereby insure the use of the generators alternately in charging the battery.

Another feature of the invention contemplates the use of an electrically driven timing device which 'functions automatically to continue the Charging of the battery for a period of two hours after the battery voltage has reached a predetermined high levell and to thereafter render the charging generator inoperative to further charge the battery,

A further feature resides in the use of an electrically driven timing device which serves automatically to delay the connection of the charging generator to the charging circuit for a predetermined interval of time after the voltage of the generator has built up to a predetermined level.

A still further feature of the invention provides means whereby, upon failure of the selected engine to start within a predetermined time and thereby drive its associated generator, the automatic controls are transferred to the second engine to cause it to start and to drive its associated generator for charging the battery.

Still another feature of the invention resides in the use of an alternating current generator or converter which serves to supply, among other things, the various electrically driven timers 'with alternating current. An auxiliary feature provides means whereby when acharging period has been completed and the controls are about to restore to normal condition, the converter is maintained operative for a predetermined interval of time to supply various ventilation controls with power.

Other features provide means for manually stopping and starting the charge from either the local unattended station or from a remotely located attended station; for manually initiating a charge of longer duration than the regular twohours charge; for controlling the ventilation of the engine room at the unattended station; for automatically initiating a charge when the engine room temperature reaches a predetermined low temperature; and for operating alarm signals at both the local and distant stations to indicate various conditions which maintain at the local unattended station.

These and other features will be readily understood from the following detailed description when read in connection with the accompanying drawings, in which:

Figs. 1 and 3 are circuit diagrams which illustrate a particular type of load furnished by the storage battery of an unattended repeater station, and the controls therefor;

Fig. 2 is a circuit diagram showing one of the engine-driven generators, its controls and voltage regulator. This equipment is included within the space defined by the broken-line enclosure. To the right of Fig. 2 is diagrammatically illustrated the ventilation controls located in the engine room;

Fig. 4 is a circuit diagram, similar to that of Fig. 2, showing the second engine-driven generator, its controls and voltage regulator. To the right of Fig. 4 are schematically illustrated the storage battery and a plurality of individual fuse connections thereto. over which various loads may be supplied with power from the battery.

Fig. 5 is a common control circuit which functions with either of the engine-driven generators v of Figs. 2 and 4; and

Fig. 6 is a block diagram illustrating the man# ner in which the Figs. 1 to. .5, inclusive,r are as;

sembled to effect a complete--worlcing,syst e'm, 'f

Each of the engine-driven generator sets de s-` either is determined by the opera-ted or released conditions of relays 53| and 533 (Fig. 5)'. When one or the other set is-selected, its dynamo functions as a motor to. crank its associated engine, and when the engine starts, the dynamo i-sdriven thereby as a generator to charge the battery.

A plurality of motor-driven timers LD Lof Fig. 2, and AS, ES, CG and CH Yof Fig.' 5 perform various control functions. Each timer has: its own separate driving motoras'is schematically indicated by the vcoil appearing immediately below the contact-controlling disc. 'These motors receive power from the. converter' which comv prises a direct current motor-r524-and an alter' nating current generator v5i?. The-latteralso furnishes current to the regulator transformers.

The condition ofthe powerplant as illustrated in the drawings, particularly,Figs. 4 -and5, is such that the gas `engine 255 and its associated-gen eratcr- Y2li) (Fig. 2) are unoperatedA-as are-also the gas engine 29E and its associatedgenerator 2|9 (Fig. 4). In other words, the batteryfdlllll` (Fig. 4) does not yet require to be recharged. Under the condition illustrated relays 53| andi533 are unoperated.

It will now be assumed that the load 'on battery 4S@ has reduced its capacity to the 'point where its voltage causes relay 500 to operateits low voltage Contact L. `Relays 500 andl54| have their windings connected in parallel across the terminals of battery ll by Way of conductors 55| and 552 and are thus controlled in their operation by the battery voltage. VRelay V55|] is adjusted to operate its low voltage contact L at some value of voltage below i60-volts and approximately 141 volts, while it closes its `high voltagevcontact H at about 157 Volts. Relay 54| is adjusted to operate its low voltage contact L at about 139 volts and its high voltage contact' at about 162 Volts.

When relay 500 closes its low voltage contact L in response to a drop in battery voltagefrelay 593 operates in an obvious circuit. -At its upper armature and front contact-relay- 5-53 establishes an obvious energizing circuit for-relay5lll -andrat its lower armature and front contact completes an operating circuit for relay-555W wayofcon, ductor 556. 5

Relay 591, at its upper armature and front contact completes a circuit to the individual alarm circuit X by way of conductor 558 to cause the operation of a low voltage alarm signal at the local unattended station. By way of its outer lower armature and front contact relay 5B1 connects conductor 559 to the alarm trunk circuit Y to cause the .appearance of a similar signal at @remote station (not shown). Relay 501, by way of its inner lower armature and front contact, locks under control of the alarm trunk circuit.

Relay 565, operated, locks in a circuit including grounded battery, winding, front contact and inner lower ,armatureof relay 585, conductor Sill, hackrcontact Vlower armature of relay 5|2, to the-Point 5|3, and thence in two parallel paths to ground, one b y way of the back contact and inner upperraranature of relay 5|4, and the other by way'of the back contact and outermost upper armature of relay 5|5, conductor 5|5, contact 5H of the motor-driven two .hour timer. CH, conductor 54.5, back Contact and upper armature of relay 5|9. under control of 'relay .514 and also under control ofthe two-hour timer CH.

Relay 2115 (Fig. 2) now operates in a circuit ex tending fromgrounded battery, winding of relay 256, `conductor '55| .and the associated normally closed contacts of test keypElZ, back `contact and outermost upper armature ofzrelayfzlla, con: ductor 25.4, conductor 419|, fronticontaot and inf ner upper armature of relay 505 to. ground. V.ReT lay 255* (Fig. 4) will also operate at this time but, as will appear presently, performs no useful function.

At its upper armature, relay 255 remet/"es-v ground from the magneto i255 of engine 20.5, thereby readying the engine Zefor operation,` At its lower armature relay 25B causes relayz' :to

operate in a circuitextending from the positiva;

or ungrounded terminal of batter-51.150,0, fuse 4.02,

conductor i522, -resistance 52|, winding of relayv conductor 2.01, front contact'. and lower 5.25, armature of relay .211B to ground.

Relay 525, operated, 'locks toground by way .of its 'lower armature and front contactunder the control of timer AS finding ground 'at contact` 523 thereof. An.auxi'liarylocking circuit :for re'- lay 525 is prepared which circuit is controlled vby relay 55S. At its upper .armature andv front 'con.

tact, relay 52) connects one terminal nfthe moe tor 524 ofthe converter GR .to the positivetere minal of battery 458 by way' .ef conductorz?, theY other terminal of the motor being-connected to the grounded terminal ofbatteryllii; by'way of conductor '525. .Thus the converter GR is :starte ed operating to 'furnish alternating'.cu'rrentito various 'instr-umentalities of the plant, such .as the motors of the motor-.driven timers'. 4' f At its outer lower armature and front contact,

relay 555 completes'a circuit to the motor windv ing 5 28 ofthree-min-ute timer ES. Thiscircuit includes the front contact and outerlower armature of relay 555, now connected t0 one terminal oi the generator 'ZLlQwer armature andbals Contact of relay .5.2.9, motor-Winding .528 andren: ductor v.5.311 which iscouneted to .the other 'ter-1 minaleofserleratcr `5.2i- Thus the' timer ESSv Started to operate topcrform a .functionQat-the f expiration of three minutes, wnicnwiii be .fully described hereinafter.

et its outer upperarmature'andfront contact relayf connects ground to thewindings Aof re.- lays 53| .and533 which relays as "hereinbefore" Thus, relay 5,05. is, locked operatedI indicated, determine which of the two charging sources SI, S2, will be selected to charge the battery. p Relay 53| accordingly operates in a circuit from grounded battery, resistance 532, winding of relay 53|, normally closed make-before-break contacts of relay 53|, to ground by way of the front contact and outer upper armature of relay 505. Relay 533 does not operate at this time since ground potential is connected to both of its winding terminals. Relay 53| locks to ground in an obvious locking circuit and opens its original operating circuit. These functions are performed by the lower armature of relay 53 A start circuit to start relay 208 (Fig. 2) may now be traced from grounded battery, Winding of relay 208, outer upper armature and back contact of relay 209, lower normally closed contacts of stop key 2li), upper normally closed contacts of test key 202, back contact and innermost upper armature of relay 203, start conductor 2|2, front contact and outer upper armature of relay 53|, conductor 534, outer lower armature and back contact of relay 2|3 (Fig. 4), conductor 405, outer lower armature and back contact of relay 2 3, conductor 2 I4, conductor 40 I, front contact and inner upper armature of relay 505, to ground. It will be observed that a similar circuit to start relay 208 (Fig. 4) is at this time opened at the back contact and outer upper armature of relay 53| so that, though relay 200 operated, as hereinbefore described, and removed the ground connection from magneto 205' (Fig. 4) of the engine 206', this engine will not be caused to function since its corresponding start relay 2&8 is unoperated.

Relay 208, operated, causes relay 2|5 to operate in a circuit which includes the heat responsive element 246 of a thermal relay whose heater Winding is indicated at 2|5. At its upper armature and front contact, relay 2 l 5 extends the conductor 456 from the positive terminal of battery 400 to the series field 2l8 of generator 2|9 by Way of the winding 2|3 0f the thermal relay and resistance 2|1, and at its lower armature and front Contact connects ground to the other terminal of generator 2|9. Thus the generator 259 is caused to function as a motor to crank the' engine 206. The ammeter 250 and its associated resistor 25| are effectively shunted during` cranking by the lower armature and front contact of relay 2 I5.

As soon as the engine 208 starts under the driving action of dynamo 2|9 functioning as a motor, the voltage generated by the shunt field 22| causes relay 2|3 to operate. At its outer lower armature, relay 253 opens the circuit to relay 298 causing this relay to restore its armature and thus to open the operating circuit for relay 2|5. Relay 2|5 accordingly, releases its armature to stop the cranking of engine 20B.

At its inner lower armature, relay 2| 3 causes relay 529 to operate in a circuit extending from grounded battery, winding ei relay 528, conductor 535y front Contact and inner lower armature of relay 2|3, to ground. At its lower armature, relay 529 opens the motor circuit to timer ES permitting the timer to reset. At its outer upper armature, relay 529 prepares the alarm trunk circuit Y for the receipt of an engine operate signal which is transmitted when relay 231 operates under control of three-minute timer LD as will be explained hereinafter. At its inner upper armature relay 529 connects ground direct to the individual alarm circuit to cause the immediate appearance of a signal at the local station.

Relay 2|3, at its inner upper armature and front contact completes an obvious operating circuit for relay 222. At its upper armature, relay 222 removes a short from the counter-electromotive force motor 229 of the regulator 221, and at its inner lower armature completes the following circuit: from the left terminal of the secondary winding of transformer 538 whose primary winding. is connected directly across the generator 521 of converter GR, conductor 226, primary winding of regulator transformer 223, closed contacts of switch 225, front contact and inner lower armature of relay 222, conductor 540, to the right terminal of the secondary winding of transformer 538. In this manner alternating current from converter GR is supplied to the regulator transformer 223 and the regulator 221 is prepared for operation. The manner in which the regulator functions will be described hereinafter, it being understood that the regulator, per se, does not constitute a part of the present invention.

At its outer upper armature, relay 2 I3 completes an operating circuit for relay 228 which causes the intake louvre in the engine room to be opened for ventilation purposes. The intake louvre motor is indicated at IM and the exhaust louvre motor is indicated at EM. With relay 228 operated the intake louvre motor functions to open the intake louvre.

As soon as the voltage of generator 2i9 builds up to approximately three volts above the voltage of battery 400, relay 230 operates and connects the lower winding of relay 233 across the generator output causing relay 233 to operate. Relay 234 now operates in a circuit from ground, Winding of relay 234, resistance 235, to the positive terminal of generator 2|9. Relay 234 in operating, connects the motor winding 235 of the three-minute timer LD across the output terminals of the generator 521 of converter GR causing the timer LD to commence its cycle of operation. After three minutes have elapsed, the

timer LD closes its contact 23S, thereby connecting the winding of relay 231 in parallel with the motor winding 236 and causing relay 231 to operate. At its upper armature and front contact, relay 231 connects the winding of contacter relay 238 between ground and the positive terminal of generator 2|9 causing relay 238 to operate. Relay 28 functions to shunt relay 230 and to connect the generator 2|9 to the battery 408, the upper winding of relay 233 being serially included in this connection. The battery 489 is now charged by the generator 2 I9.

When relay 231 operates, as described, it completes the connection from ground at the front contact and inner lower armature of relay 2i3 t0 the lead 259 which connects with the upper armature of relay 529. With relay 529 operated, an engine operate signal is transmitted over the alarm trunk circuit Y. y

Thus far the system disclosed has been described under normal conditions of operation and it has been disclosed how, with relays 53| and 533 in the positions illustrated, relay 53 will operate in response to a low voltage condition of battery 400 as evidenced by the operation of voltmeter relay 500 to its low voltage contact) L, and that three minutes after generator 2 I9 builds up a voltage slightly in excess of that of the battery 400, the timer LD functions to connect the battery to the generator for charging thereby. Also have been described the transmission of low volt- 2|8' of generator 2|9 causing the generator to function as a motor to crank the engine 206. As previously described, the ammeter 250 and its associated resistor 25| are eiectively shunted during cranking due to the engagement of the lower armature of relay 2|5 with its front contact.

As soon as the engine 206' starts under the driving action of dynamo 2I9 functioning as a motor, the Voltage generated by the shunt field 22|' causes relay 2|3 to operate. Relays 208' and 2|5' thereupon deenergize and the cranking of the engine 206' is stopped.

The operation of the circuit (Fig. 4) is identical with that of the circuit of Fig. 2, previously described, and it is believed unnecessary to describe it in detail further. Relay 21.3' performs similar functions to those performed by relay 2l3 and the generator 2|9 continues to charge the battery under control of the timer CH in a manner now apparent. At the expiration of the two-hour interval, which begins when the voltmeter relay 50|) operates its high voltage contact H, the charging of the battery is discontinued and the circuit is returned to normal condition. When relay 595 restores its armatures, relay 533 releases. This condition will nd relays l and 533 predisposed to cause the selection of the engine-generator set Sl ior use to charge the battery when the battery Voltage again reaches the low voltage level at which relay 529 operates its low voltage contact L. When this happens, relay 53| will reoperate which is the condition under which the earlier description was based and which resulted in the operation of the engine-generator set Si to charge the battery.

It is apparent from the description thus far advanced that the engine-generator sets Si and S2 are employed alternately to charge the battery .88 and that relays 53| and 533 function to insure this alternate use of the charging sources and to preclude the successive uses of either.

rlhe above procedure applies when the engine selected for use in charging the battery 400 starts readily. If the engine 206, for example, should fail to start, cranking thereof continues until the thermal relay, comprising the heat responsive element 24S and the operating coil 2|6, functions to open the operating circuit for relay 2|5. Relay 2|5, released, disconnects the battery 4S@ from the generator 2|El and cranking or the engine 295 is discontinued. The timer ES continues to operate for three minutes, when it closes its contact 561,' whereupon relay 283 operates in a circuit extending from ground-ed battery, lower winding of relay 223, conductor 26|, front contact and inner upper armature of relay 53|, to ground at contact del of timer ES. Relay 223, operated, locks to ground at the upper normally closed contacts of stop key 2|0. A circuit may now be traced from ground, inner upper armature and front contact of relay 535, conductor 40|, conductor 2li, back contact and outer lowerarmature of relay 2|3, conductor 425, back contact and outer lower armature of relay 2|3, conductor 534, outer upper armature and front contact of relay 53|, conductor 252, innermost upper armature and front contact of relay 223, conductor 239, middle upper armature and back Contact of relay thence through the upper normally closed contacts of key' 2&2 lower normally closed contacts of key 2| ll', back contact and outer upper armature of relay .229',

to battery and ground through the Winding of relay 208'. This last-mentioned relay then functions to start the gas engine-generator of S2 in the manner previously described. The battery 400 is then charged by the generator of S2 as previously described.

Relay 203, operated, causes relay 51D to operate in a circuit extending from grounded battery, Winding of relay 510 conductor 52|, outer lower armature and front contact of relay 203 to ground. Relay 510 operates and establishes obvious circuits to the individual alarm circuit X and the alarm trunk circuit Y over which engine failure alarms are operated.

Until the attendant manually releases relay 203 by operating key 2|0,each time the circuit calls for a charge the engine, which has not failed, will start rst through relay 53| operated, then through relay 53| released. It both engines fail, both relays 283 and 253 would operate and lock and a low voltage alarm will supplement the engine failure alarm.

When an engine, such as engine 226 of Fig. 2, for example, is running, its output is regulated by the automatic regulator designated 221 in Fig. 2. This regulator, per se, which does not constitute a part of the present invention, comprises a full 'wave rectiiier tube 283, a regulating tube 253, an amplifier tube 259 and a CEMF motor 229. The action of this regulator is such that with voltages below the desired value, the CEMF motor includ-ed in the shunt eld of the generator 2|9 raises the generator voltage by reducing the potential drop across its armature. If under such a low voltage condition, the generator output should exceed the setting of the ammeter relay 250 (about 32 amperes), relay 242 would operate in a circuit extending from the positive side of the charging circuit, resistance 242, winding of relay 246, contact 239 of arnmeter relay 220 to ground. Relay 242 operated, completes an operating circuit for relay 24| eX- tending from ground, armature and front contact of relay 242, winding oi relay 24|, resistance 243, to the positive side of the charging circuit. Relay 24| functions to transfer the regulator to current regulation. Relay 24A, operated, locks up in a circuit extendingfrom the positiv-e side of the charging circuit, resistance 243, winding, front contact and innermost armature of relay 24|, conductor 245,- back contact and outer upper armature of relay 5| 2 to ground. Relay 5|2 is under the control of the high voltage contact H of voltmeter relay 54|.

Current regulation is accomplished by applying a iixed bias direct to the grid el-ectrode of the amplifier tube 2551 of the regulator 22'! such that constant output willbe maintained from the generator 2|9. This bias is adjustable to give an output of about thirty amperesA by varying the resistance 25|. The bias appliedto the amplifier grid is the differential between the potential drop across the resistance 25l and ammeter 25D as compared to a standard three volt grid battery 252, the connections to the amplifiers for thesevpotentials being completed at the two upper frontcontacts and armatures of relay 24|. A tendency of the generator' output to increase will reduce the negative grid Voltage applied to the amplifier tube 2541 thereby increasing its plate current and applying a more negative bias to the regulator tube 253. This will reduce the current in the regulating eld 254 so that it will have less bucking effect, thereby increasing the potential drop across the CEMF motor and reducing the generator output by reducing its field strength. A tendency of the generator output to fall-off will, of course', have the' opposite effect so that constant output is maintained until :the battery voltage reaches a level such as to cause voltmeter relay 54| to operate its high voltage contact H. Relay |2 thereupon operates in an vobvious circuit and at its upper armature and back contact opens the locking circuit for relay 24|. Relay 24| accordingly releases its airmatures, transferring the regulator control backto voltage regulation. The regulator, in this application, is adjustable to regulate the battery at 160 volts, measured 'at the battery terminals, which is below the point at which relay 54| operatedV (162 volts), so that relays 54| 'and 512 will release Vas soon as relay 24| releases.

Relays500, 5|4 and 550, which operated when the voltage reached 157 volts under current regulation remain operated during change over from current'to voltage regulation and ground potential at the upper armature and back contact oi relay 5| 9 is carried by way of conductor 5|8, contact 5H of timer CH, conductor 516, outermost upper armature and back contact of relay 5|5, front contact and upper armature of relay 550, conductor 5|0, inner lower armature and front Contact of relay 505 to the winding of relay 505 and grounded battery, thereby maintaining relay 505 operated and keeping the engine 2|Jt` running. n

As previously described, when relay 500 operated its high voltage Contact H and relay 5M operated, the circuit to the motor winding 55| of the timer CH was completed and the timer functions to maintain the charge on'k the battery for a two hour period. Thus a two hour charge is maintained above-157 volts even `though the voltage of 162 volts is not reached by that time.

Arrangements are also made to start the engine manually'either at the local unattended station or at the remote station over the alarm system. The engine is started from the distant or attended station by the operation of an engine start key which by way ofthe alarm trunk circuit Y causes the energization of the operating coil of thermal relay 56| over conditions 550. When the heat responsive element of this relay functions to close its contact an obvious operating circuit for relay 562 is completed, At its lower armature and front contact, relay 532places keys 2| and 202 are then restored to their norground on the conductor 506 causing relay 505 to' operate. Thus the engine is started in the same manner as described above when starting from the low voltage contact L of relay 54|. This means of starting is provided as a maintenance feature to permit remote starting control. Operation of the engine will be indicated by the engine operate alarm signal and failure to start will be indicated, after three minutes, by the engine failure alarm in the manner previously described. Once started, the engine will ru'n until the battery is charged to the regulated value when the engine will be cut off as described above. Y l

The engine may be manually started at the local station by operating the test key 202 to the test position. With key 292 Operated, relay 200 operates direct to ground at the contact of key 202 associated with conductor 20|. Relay 203 operates over' an obvious circuit and relay 208 operates in a circuit extending from grounded battery, winding of relay 208, outer upper armature and back contact of relay 209, lower normal contact of stop key 2I0, first upper alternate contact of test key 202, back contact and outer 'mal positions.

' Manual operation may be employed at infre- `quent intervals VforY overcharging toreturn the batteries to a full charged gravity condition. Both engine sets Si and S2 may be run rat once under manual control at the local station but only one can be operated at a time automatically.

lEach engine is provided, among other safeguards, with a low oil pressure contact, 'such as 266, which furnishes ground to the contact of relay 261 so that should this occur when relay 2551 is operated, an obvious operating circuit is completed to relay 209. Relay 209 operates to ground the magneto 2%5 and thus stops the engine 20S. Relay 209, operated, also opens the circuit to relay 208 to prevent cranking, and by way of its lower armature and front co-ntact and the contacts of key 21| locks to ground at 26B and thereby maintains the engine 20B out of service until an attendant operates key 21|. Low oil pressure when the engine is not running, and when starting, will have no effect as relay 261 will be released until relay 231 operates to cause contactor 23S to connect the generator to the battery, as previously described. On release of relay 231 when the engine shuts off under its normal control, relay 261 releases before relay 209`can operate from reduced oil pressure. Under this condition of low oil pressure an engine failure alarm is given after timer ES operates as a result of the engines failure to start.

In addition to the automatic two hour charge at approximately 2.3 volts 10er cell each time the engine operates as previously described, provision is made for a monthly twelve hour check charge under automatic control by manually operating the auto charge key 511. This key, while operated, holds ground on relay 505 to maintainthis relay locked to keep the engine running and also causes relay 5|5 to operate. Relay 5|5, operated, locks to ground at key 511 if the battery voltage is below the high Contact value of relay 500, otherwise it locks to ground by way of the outer upper armature and front contact of relay 514. Relay 5|5, operated, causes relay 518 to operate which, in turn, operates and locks relay 5|9.

Relay 519 at its upper armature and front contact connects ground to contact 519 of the timer CG to hold relay 505 operated after key 511 is released. Relay 5|5, at its inner lower armature and front contact, prepares an operating circuit for motor winding 580 of timer CG which circuit is completed when relays 50G and 5M operate incident to the battery reaching the voltage at which relay 500 closes its contact H. Thus when the battery reaches this voltage the timer CG starts to function. The charge will continue for twelve hours when the timer CG breaks its contact 519. 'Ihe generator regulator will hold current regulation as previously described until relay 54| operates its high voltage control H and will then transfer to voltage regulation at approximately volts.

When the timer CG removes locking ground from the winding of relay 505, relay 505 releases, stopping the engine and causing the generator to engine.

be disconnected from the battery. On fall of voltage due to battery -discharge relays 500, I4 and 550 release opening the locking circuit to relay 5I5. Relay 5I5 releases causing relay 518 to release. Relay 599, however, is held operated to ground at contact 515 of the timer CG, thereby maintaining relay 5I9 operated. Thus the circuit to the motor winding 589 of timer CG is maintained closed and the timer is continued operating until it opens the contact 515 and restores to the position shown. Breaking this circuit releases relay 599 which in turn releases relay 5I9 returning the circuit to normal.

Provision is made for stopping this charge from the attended or remote station, if it is desired to do so, and if the battery voltage is 157 volts or more, by operating the engine start control at the remote station (not shown) which causes thermal relay 56| to operate. Relay 56|, in turn, causes relay7 552 to operate which, at its outer armature and front contact shunts down relay 5 I 9 causing it to open the holding ground on relay 505. -Relay 565 thus is deenergized and in releasing its armatures stops the engine in the manner previously described. Relays 500, 5M. 559, 5I5 and 518 restore to normal. On manual release of the start control at the remote station relay `562 releases returning the circuit to normal. Automatic means for maintaining the engine room above a predetermined temperature de- 'grees F.) are provided by running the engine to charge the batteries any time room temperature is belovv this value. At the predetermined temperature; thermostat 513 closes its contact to operate relay 505 which then functions to start the engine. Theengine runs von the usual charge cycle'before stopping. l

Arrangements are made for manual operating and regulating the engine set. Key 2m (stop) provides means for locking the set SI so it cannot start and for transferring the automatic controlrso the, other set AS2 will take its place, by operating relay 203. Key 202 (test) provides means for running under test conditions locking out the automatic control and transferring it to theV other set. Manual regulation of the generators maybe accomplished by actuating switch 280 to its alternate position and adjusting the field rheostat. l

In'anearlier description, it was pointed out that when` the engine, such as engine 295 of set SI is operating, relay 2I3 operates to cause the operation of relay 228Which functions to control the .opening of the intake louvre of the operating the large broken line enclosure and which includes vrelay 22,8 also provides control for Ventilating the yengine room. Thermostat 282 which is set at 90 degrees F. operates relay 283 and in turn 284 when the engine room reaches this temperature. Relay 284, operated, closes contacter 299 to start the fan 298 and opens the exhaust louvre. The fan runs until the engine stops or until the room cools to the point Where thermostat 291 opens theholding contact of relay 283, the contact of thermostat 282 having already opened. When relay 283 releases, relay 284 releases stopping the fan and closing the exhaust louvre.

A liquidometer gauge 295 closes its contact in the event oi low gasoline supply. Relay 294 operates to furnish alarms indicating low fuel supply.l Relay 293 operates on discharge fuse failures to furnish alarm signals.

As hereinbeiore indicated Figs. 1 and 3 are representative of a load circuit supplied from the That portion of Fig. 2 to the right of i battery 40B, and the controls therefor. Particularly, the loads are indicated schematically by the terminals A, B, C and D which are intended to connect with the filaments or the repeater amplifiers located at the unattended station.

At the lower section of Fig. 1 there are illustrated schematically three converters I, 2 and 3. Converters l and 2 function to supply 6G volts alternating current to their respective loads Whose terminals are indicated at A. B and C, D respectively. Under emergency conditions, causing loss of voltage from either converter I or 2, its load will be transferred to the standby converter 3.

Each converter consists of a direct current motor II, I2 or I3 and an alternating current generator 2l, or 23. It will be observed that the right-hand terminal of motors II, I?. and I3 are connected directly to conductor I4 by Way of conductors l5, l5 and I1, respectively, conductor I4, in turn being connected to the rounded terminal of battery 495. The left-hand terminal of motor II is connected by Way of conductor I9, iront contact and armature of relay I9, front contacts and left armatures of relays 29, 24 and 25, conductor 25, fuses 21 to the ungrounded terminal of battery The left-hand terminal of motor 2 is connected to the ungrounded terminal of battery Zeil by Way of conductor 23, front contact Iand armature of relay 29, front contacts and left armatures of relays Sil, SI and 32, conductor and fuses 5Fl. The left-hand terminal of converter I3 is normally open circuit-ed. Thus the motors II and i2 normally operating to drive their respective generators 2l and 22. rlhe right-hand terminals of generators 2i and 22, and also of generator 23, are connected to the grounded load terminals of sets 11,13, C and D by way of common conductor 35. The left-hand terminal ci' generator 2l is connected to the ungrounded terminals ci sets A and B by way of variable resistance back contact and left armature of relay 31, conductor and fuses and @u respectively. The left-hand terminal oi generator E?. is conr nected to the ungrounded load terminals of sets C and D by Way of variable resistance ffl, back contact and right armature of relay conductor i3 and fuses il and respectively. The lefthand terminal of the generator 23 is normally open circuited at the back contacts and left and right armatures respectively oi relays 31 and 42. The loads indicated by the terminals A and B are thus supplied with alternating current from generator 2i while the loads indicated by the terminals C and D are supplied with alternating current from the generator 22. Standby generator 23 is normally non-operating.

It will be noted that the relays 29, N and 2.5 associated with converter 2I are normally operated and at their left armatures short circuit the resistors 5, 'l and G8 respectively. Similarly relays 30, 3l and 32, associated with converter 22, are normally operated and at their left armatures short circuit resistors 49, and 5I. Thus the iull battery voltage of 152 volts is normally supplied to the converter motors I I and I2.

Voltmeter relay HL has its operating Winding normally connected across the input to converter I While voltmeter relay LH'has its operating Winding normally connected across the input to converter 2. These relays function to maintain the input voltages Within 137-144 volts as the battery voltage varies from 141-160 volts on its chargedischarge cycle of operation.

With the relays in the control circuits (Fig. 2)

in the conditions illustrated and the battery 480 charged to the point where relay HL makes its high contact 52, relay 53 operates in an obvious circuit causing relay 54 to operate in a circuit extending from grounded battery, winding of rc1 lay 54, back contact 'and left armature of relay 55, conductor 55, front contact and armature of relay 53, to ground. Relay 54, operated, locks in an obvious circuit and at its left armature, opens the 'energizing' circuit for relay 25. Relay 25 releases and at its left armature removes the short from resistor 48 thereby reducing the input voltage toconverter I by the drop in this resistor. With the reduced input voltage relay HL restores to normal, releasing relay 53. At its right armature and back contact relay 25 causes relay 55 to operate in an obvious circuit.

When the battery 488 charges to a point Where relay HL again closes its contact 52, relay 53 reoperates to cause relay 51 to operate in a circuit extending from grounded battery, winding of relay 51, back contact and left armature of relay 58, front contact and left armature of relay 55, conductor 55,to ground by way of the front contact and armature of relay 53. Relay 51 locks operated in an obvious circuit. At it-s left armature and back contact relay 51 causes the release of relay 24, which relay at its left armature inserts resistor 41 in the input circuit to converter I to lower the input voltage in the same manner as relay 25, as previously described.

When the battery 400 charges to the point Where relay HL again operates its contact 52, it being understood that contact 52 and, in turn, relay 53 are released on the reduced voltage, relay 55 is reoperated causing relay 59 to operate in a circuit extending from grounded battery, winding of relay 59, back contact and left armature of relay 60, front contact and left armature of relay 58 (operated when relay 24 restored its right armature), front contact and left armature of relay55, conductor 56, yarmature and front contact of relay 53 to ground. Relay 20 inserts resistors 46 in the input circuit to converter I and at its right armature causes relay 60 to operate A in an obvious circuit. Thus the input voltage to converter I is reduced a third time.

The circuit remains in this condition until the battery voltage falls on cessation or charge to the low voltage contact point of relay HL. At this time relay HL closes its contact 5I to complete an obvious operating circuit to relay 62. At its armature and front contact relay 62 connects ground to the lower terminal of relay 59 by way' of the front contact and right armature of relay 69 causing relay 59 to be shorted down. Relay 55 in restoring its left armature causes relay 20 to reoperate. At itsleft armature yand front contact relay 26 shorts resistor 45 thereby raising the input voltage to converter I by the drop in resistance 45. At its right armature and front contact relay 26 causes relay 60 to be deenergized. As the input voltage drops, relay opens its ontact 6I causing relay 62 to restore its armaure.

When the battery voltage falls to the point where relay again makes its low voltage contact 6l, relay 62 reoperates to connect ground to thelower terminal of relay 51 by way of the right armature and back contact of relay 68 and the right armature and front contact of relay 58. Thus relay 51 is caused to release its armatures. Relay 51, at its left armature and back contact reestablishes the operating circuit for relay 24 which functions to remove resistor 41 from the input circuit to converter I and thereby increase th input voltage in the same manneras de scribed in connection with the operation 'of relay 25. Relay 56 releases when relay 24 operates its right armature'and relays HL and 52 release onthe' increase in voltage.

When the low voltage contact BI of relay HL is closed for the third time due to a drop in battery'voltage, relay 62 is reoperated causing the connection of ground to the lower terminal of relay 515i by way of the right armature and back contact of relay 68, right armature and back contact of relay 58, andthe right armature and front contact of relay 55. Thus relay 54 is deenergized and releases its armatures; At its left armature and back contact relay 54 reestablishes the operating circuit for relay 25 causing relay 25 to operate. At its left armature and front contact relay 25 shorts resistor 48 causing an increase in the input voltage to converter I and at its right armature it causes the release of relay 55. Thus the-circuit is returned to th conditionillustrated. u

Operation of the voltage relay control for con y verter 2 is identical with that just described and it is deemedunnecessary to include herein any description thereof. It is apparent that the unidentified relays appearing in Fig. 2 to the right of relays-29, 38, 3I and 32 are identicalhin operation and purpose to relays 59, 65, 51,58, 54 and 55 Vwhich appear to the right of relays 20, 24 and 25.

Under emergency conditions causing lossof voltage from either converter I or 2, its load will be transferred to the standby converter 3. This is accomplished on converter I, for example, when relay 18, which is normally held operated by the output of converter I through rectiiier 1I, releases on loss of voltage and causes relay 12 to operate in an obvious circuit. Relay 12 functions to provide no voltage alarm (not shown) and at its right armature completes an operating circuit for relays 31 and. 13 (Fig. 2). This circuit extends from grounded battery at converter transfer key 14, windings of relays 31 and 13 inparallel, right armature andA front contact of relay 12, conductor 15, front contact and inner armature of relay 16, to ground. Re-

lay 16 is normally operated being included Iin the input circuit to converter 2. Relay 31, at itslft armature, transfers the load conductor 38 from the left terminal of generator 2| to the lefttrminal of standby generator 23, it being understood that the right terminal ofy generator 23 is connected* to the ground as previously described.

Relay 13, operated, opens its left normally closed armature contact causing relay I9 to rlease.` Relay I9 thus functions to disconnect battery from motor II of converter I, and from the winding of relay 11 causing the latter to 'restore its armatures. At its inner armature and .front Contact relay 13 locks operated until the key 14 is operated manually. At its outer right armature, relay 13 transfers the winding of voltage relay HL to the battery input for converter- 3. At its inner right armature, relay 13 completes an obvious operating circuit for relay 19. At its outer left armature and front Contact, relay 13 connects the winding of relay 80 to the input circuit to converter 3 causing relay 80 to operate. Relay 80, operated, completes the connection of battery to the converter motor I3 causing the converter 3 to start, and connects battery to the windings of relays 8l, 82 and 83. With relay 19 operated, relays 8|, 82 and 83 are now ctlled from the voltage, relay HL in the same manner as previously described in connection with relays 20, 24 and 25. y

Relay 19 at its three armatures and front contacts, connects one terminal of each relay 8|, 82 and 83 to ground at the right armatures and back contacts of relays 59, 51 and 54 respectively, the other terminals of relays 8 l, 82 and v83 being connected to the battery lead toconverter 3 by way of the front contact and armature of relay 80. Under this condition relays 54, 51 and 59 will respond to closures of the high voltage contact 52 of relay HL to cause relays 20, 24 and 25, and 8l, 82 and 83 to restore their armatures but only the last three relays will function to control the input voltage to converter 3.

As soon as converter 3 builds up its voltage relay 1U will operate through rectifier 1l cutting off the no voltage alarm (not shown). When relay 31 operated, it connected ground at its right armature and front contact to the winding of relay 84 which at its armature and front contact completed a circuit (not shown) in which a transfer signal is operated. The transfer alarm remains operated since relay 31, like relay 13 is locked operated.

Trouble on converter 2 causing loss of output voltage will transfer its load to the standby converter 3 in a manner similar to that described for converter l except that relay 13 is unoperated causing relays 8l, 82 and 83 to operate with relays 30, 3l and 32 instead of with relays 20, 24 and 25 as just described.

Safeguards are provided to prevent transfer of both converters I and 2 to the standby 3. If both converters l and 2 should fail, the first to fail will transfer to the standby as described and the other will be kept from transferring by the release of either relay 11 or 16 which removes ground from the transfer relay. Y

Failure of a discharge fuse, 39, 40, 44 Or 45 will cause either relay 86 or relay 81 to operate which causes relay 88 to operate to transmit a "no voltage alarm (not shown).

Invthe event of maintenance on the regular converters l and 2, the load is transferred to the standby converter 3 by operation of the converter transfer keys 18 or B9. The loadwill then be carried by converter 3 until the converter transfer return key 14 or 90 is operated. Either regular converter l or 2 may be operated for maintenance purpose by actuating its respective key 9| or 92. While in this Position the lamp 93 or 94 is operated to assure the attendants returning the key to normal before leaving the station or returning the load to its regular converter. A switch 95 and guard lamp 96 serve similar purposes in connection with converter 3.

Keys 91, 98 and 99 are provided to permit the voltage of each converter l, 2 and 3 to be read on the meter V.

What is claimed is:

1. In a power supply system in which a storage battery is charged at recurring intervals the occurrences of which intervals are determined by the voltage condition of the battery, duplicate means for charging the battery, control means for automatically rendering each of said duplicate charging means operative to charge said battery only during different alternate intervals whereby neither of said duplicate charging means operates to charge said battery during successive intervals, and means responsive to the battery voltage for controlling said control means.

2. In a power supply system, a storage battery supplying current to a load circuit, a first source of power for charging said battery, a second source of power for charging said battery, and control means responsive to a predetermined low voltage condition of said battery for causing the connection of said first source of power to said battery for a predetermined period of time to charge said battery, said means functioning automatically when said battery again reaches the said predetermined low voltage condition after the expiration of the said predetermined period of time for causing the connection of said second source of power to said battery to charge said battery.

3. In a power supply system, a storage battery supplying current to a load circuit, a first internal combustion engine-driven generator, a second internal combustion engine-driven generator, means responsive to a predetermined low voltage condition of said battery for rendering only said `first engine-driven generator operative to charge said battery, and means for maintaining said first engine-driven generator operative to charge said battery for a predetermined interval of time after the voltage of said battery reaches a predetermined high level and for thereafter rendering sa1d first engine-driven generator inoperative to charge said battery, said first means operating automatically in response to a subsequent occurrence of the said predetermined low voltage condition of said battery for rendering only said second engine-driven generator operative to charge said battery.

4. In a power supply system, an electrical storage battery supplying current to a load circuit, a pair of charging generators, an internal combustion engine for each of said generators each having an ignition circuit, means responsive to a predetermined low voltage condition of said battery for completing the ignition circuit of one of said engines and for causing its corresponding generator to operate as a motor and to crank said engine, means operating upon failure of said engine to start within a predetermined period of time for discontinuing the cranking of said engine by said generator, a motor-driven timer 0perating during the cranking of said engine, and means controlled by said timer when said engine fails to start for causing the other of said generators to be driven by its corresponding engine to charge said battery.

5. A power supply system comprising an electrical storage battery supplying current to a load circuit, a pair of charging generators, an internal combustion engine for each of said generators and each having an ignition circuit, means responsive to a predetermined low voltage condition or said battery for completing the ignition circuit to one of said engines and for causing its corresponding generator to operate as a motor to crank said engine, means operating should said engine fail to start and drive said generator within a predetermined interval of time for stopping the cranking of said engine, a motor-driven timer, means controlled by said motor-driven timer for causing the other of said generators to function as a motor to crank its corresponding engine, and means responsive to the voltage built up by said other generator when its corresponding engine starts for stopping the cranking of said other engine and for subsequently connecting said other generator to said battery to charge it.

.6. A power supply system comprising an electrical storage battery supplying current to a load cir cuit, a charging generator, an internal combustion' engine having Y anignition circuit, forV driving said generator,- controlmeans autrrmiatioallyY responsive to aV givenr low voltage conditioner said: battery tov completed the ignition circuit' of said engine-and to-continuously crank said engine, means responsive to the building up ofapredetermined output voltageby saidgenerator driven bysaid engine when itlstarts; to-preventfurther cranking of saidl engine; a motor-driven' timer, means responsive togenerator voltage of predetermined-'-level for operating said motor-driven timer to causeittoinitiatea-timing cycle o-predetermined length, and means controlled by saidmotor-driven timer when it completesits timingA cycle` forv completingY the chargingY circuit from Saidgenera-tor to saiddbattery.

'E1n combination'in apower supplyv system, a storage-battery supplying currentl to a load" cir'- cuii'g-a pairof charging sources for said battery, meansiresponsive-td a predetermined low voltage condition of-s-aid: battery for connecting one of saidi charging sources tesaid battery, a timing device, meansL respons-ive to apredeterminedhighvoltage condi-tion or"J said` battery for placing'theconnection ofI said one'o'f# said charging sources to said battery under the control' of said timing device; andN for initiating the operation'ofsaid timing device,` meanscontrolled' by saidtimingY dev-ic'esatthe expiration ofa predetermined time interval. foliowingfthe initiation of its operation for` disconnecting said'L onesof-y said charging batteryforcompleting the ignition== circuit-ifo 'saidi engine andl for crankingsaid'iengi'nel whereby said; engine starts and drives said generator -tr'rhargeA said battery; means'responsive-to a-predetermined` highvoltage 'conditionner said batteryfer con nectingsaid motor-driven timer t"osaid converter` whereby 'saidtimerstarts ad timing cycle; andy means controlled@ by said t'i'merwhenitL completes' its timing 'cycle `for? i'nterrupting.` the l ignition` cir-- cuit tosaid` engirn-:fll wherebysaidA engine discorr-V tinues thedriving' ofv 'said-generator and` the' charge tofsaid battery is stoppecla predetermined: interval of-I time after/said battery reaches the;

saidpredetermined'high voltage condition:4

9: In combination; anr eiectrioai storagewbat; tery, a chargingV generator, an internalbombustion;v engine having an` ignitioncircuit; fordriving saidgenerator; a normallystationary motordriven timer; asecond motor-,driven timer. ,a corrverter-forsuppiyingsaidmotoredriven timers witr operating current', contro" mea-ns includingfa relay` responsive to a` givenj low,- voltage Vcondition of saidtbattery for completingjthe ignitionA circuit to said" engine, for connecting` said generator and thev inputterminals of'said convertertosaidbattery whereby said engine functions after'starting toA drive said- 'generatorA to charge said-battery and' saidl` converter is renderedJ operative to suppi'yfoperating current to' said'motor-driven timers* means responsive toa. predeterminedhigh Vvoltage condition ofi said batteryior connecting saidfy rst motor-driven timer tothe'V output' terminals; of"

said converter whereby saidtinier startsa timing cycl'ameans, controiledby said'timer when' itcpmpletesj its; timing cycle for disabling said ignition,

- from saudibattery,`

HARRY' SPENCER. 

